Grinding machine with oscillating rotary work holder



Dec. 3, 1957 s. MESSERSCHMIDT GRINDING MACHINE WITH OSCILLATING ROTARYWORK HOLDER 4-Sheets -S'heet 1 Filed Jan. 14:, 1955 INVHW'OP 6BA$TIANME-SSBPSCHMZ'DT Dec. 3, 1957 I GRINDING MACHINE WITH OSCILLATING ROTARYWORK HOLDER s. MESSERSCHMIDT Filed Jan. 14, 1955 4 Sheets-Sheet 2 FIG 6Hill-Ill" JTTORA/EX 1957 s. MESSERSCHMIDT 2,814,915

GRINDING MACHINE WITH OSCILLATING ROTARY WORK HOLDER Filed Jan. 14, 19554 Sheets-Sheet 3 INV ENT OR SEBASTIAN MESSERSCHMIDT ATTORNEY 2,814,915GRINDING MACHINE. WITH OSCILLATING ROTARY WORK HOLDER Filed Jan. 14,1955 Dec. 3, 1957 s. MESSERSCHMIDT 4 Sheets-Sheet 4 MEN ORqassssns'cnmofi' SEBASTIAN ATTORNEY United States Fatent GRINDINGMACHINE WITH OSCILLATING ROTARY WORK HOLDER Sebastian Messerschmidt,Schweinfurt, Germany Application January 14, 1955, Serial No. 481,925

Claims priority, application Germany February 15, 1954 8 Claims. (Cl.51-97) The invention relates to a swivelling mechanism for machinetools, particularly grinding machines.

Hitherto rings, especially those for ball bearings, were internallyground by the plunge-cut or oscillation method.

These methods are open to a number of objections and it is the object ofthe invention to overcome these in the manner hereinafter described withreference to the accompanying drawings, in which:

Fig. 1 is a diagram illustrating the known oscillation method;

Fig. 2 shows the grinding track produced by the method illustrated inFig. 1;

Fig. 3 shows the grinding track which it is desired to produce;

Fig. 4 is a diagram of a swivelling mechanism according to theinvention;

Fig. 5 is a vertical section through the head of the mechanism;

Fig. 6 is a detail view showing the cam disk arrangement on the kingpin;

Figure 7 shows the gearing drive to king pin 8;

Figure 8 shows the linkage interconnecting the king pin 8 and thecontrol shaft of the gearing of Figure 5;

Figure 9 shows the worm for driving the worm gear of the gearing shownin Figure 5;

Figures 10 and 11 show the linkage interconnecting the gearing of Figure5 to the control shaft of the chuck of Figure 12, and

Figure 12 shows the drives for the grinding wheel and for the chuck.

According to Fig. 1 the ring 1 to be ground is held in a chuck 2. Thegrinding wheel 3 extends into the ring 1 and is driven by a motorthrough the intermediary of a shaft 4. The profile of the edge of thegrinding wheel 3 corresponds to the radius R of the inner surface of thering 1 to be ground.

When grinding the ring both the grinding wheel 3 and the ring 1 rotate.To maintain the radius of the grinding wheel on the profile thereofeither the grinding wheel 3 or the chuck 3 is swivelled about the centre0 while the grinding wheel 3 and the ring 1 rotate, the range of angulardisplacement of the centre line I-I of the grinding wheel being locatedbetween the dot-dash lines IIII and lIIIII. The advantage of theswivelling movement is that a certain radius R of the ring 1 has to besubstantially retained. This is possible because the wear of thegrinding wheel during the grinding operation is in accordance with theradius R. An objection to this method is that by swinging the workpieceor the grinding wheel the grinding track on the inner surface of thering 1 is not rectilinear but in wave-like lines as shown in Fig. 2. Aring ground in this manner is unsuitable for a ball bearing fortechnical reasons in the operation and running of the balls.Consequently it is endeavoured to grind the ring so that the grindingtrack is rectilinear as illustrated in Fig. 3.

In the case of the plunge-cut method, the swivelling movement about thepoint 0 is eliminated (Fig. 1).

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Consequently a rectilinear grinding track similar to that shown in Fig.3 is obtained. This method, however, is likewise not satisfactorybecause it is difiicult to obtain with the desired accuracy a certainradius R in the ring.

It has now been proposed to subject the inner surface of the ring firstto an oscillating preliminary or rough grinding on one machine and thento a subsequent or final plunge-cut grinding on another machine.Although the advantages of both grinding methods are obtained by thissubsequent grinding operation, the necessity of rechucking the workpiecerepresents an undesirably great loss of time. To reduce this, bothoscillating and plunge-cut grinding operations were carried out on thesame machine. During the dipping or plunge-cut grinding the oscillatingmovement must cease. Therefore an arrangement must be provided whichallows the swivelling'movement to be controlled as required. Seeing thatthe known machine is serviced, that is the swivelling arrangement isswitched on and oil, by the operator, 7

the position in which the swung part comes to a standstill relatively tothe part which is not swung when the machine is stopped is dependentupon the skill of the operator. Consequently, although the necessity ofrechucking the workpieces is done away with when rings are subjected toan oscillating preliminary rough grind ing and a plunge-cut finalgrinding on a single machine, the objection nevertheless arises thateach time the swivelling device is switched off after the oscillatinggrinding operation, the swung part must be brought once more into itsnormal position. This, on the one hand, wastes time and, on the otherhand, hinders production. Therefore it must be endeavoured to make thecontrol of the grinding operation independent of the operator.

This is attained according to the invention in that the swivellingmechanism of a machine tool is equipped with an arrangement whichautomatically controls the starting and duration of the swingingmovement.

The grinding machine disclosed includes a grinding wheel 65 and a chuck2. The respective drives for the grinding wheel and the chuck are shownin Figure 12. The grinding wheel 65 and grinding spindle 64 are drivenby motor 60 and belt and pulley gearing 61, 62, 63. The chuck is rotatedby means of a motor 54 and belt and pulley gearing 56, 70, 57, 58, andshaft 59 upon which the chuck is mounted. The chuck is also given anoscillatory movement about a point 0 as indicated diagrammatically inFigure 4. This point 0, as it relates to Figure 12, lies on the axis ofshaft 69 and the oscillation about this point takes place in a planenormal to the plane of the paper. The pulley 58 and the shaft 59 areincluded in this oscillatory movement which is permitted by aresiliently movable mounting of pulley 70. The oscillatory movement ofthese members is brought about by the oscillatory movement of shaft 69on its axis caused by crank pin 7, connecting rod 5, eccentric pin 67and eccentric 68 carried by the shaft as shown particularly in Figures10, 11, and 12. The oscillatory movement of chuck 2, pulley 58 and shaft59 is caused by the oscillation of a crank arm (not shown) on the end ofshaft 69, the arm constituting a supporting base for the chuck, pulleyand shaft. Such a supporting base is fully disclosed in applicantsSerial No. 586,521 now pending before the Patent Ofilce. The radialdistance of the crank pin 7 from the axis of rotation S can be changedwhile the crank 6, shown in Figure 4 and comprising parts 38, 43, shownin Figure 5, is turning. The crank gear is controlled by a kingpin 8.This pin carries two cam disks 9 and 10 with toe cams 11 and 12. Theselatter cooperate alternately with corresponding counter earns 13 and 14on a control fork 15. The control fork 15 is connected to another fork16 and pivotally mounted at 17. The fork 16 is provided with catch pins18 and 19 which serve for shifting a shaft 20 by means of a sleeve 21.The shaft 20 carries at its other end a clutch member 22 which can mesheither with a bevel wheel 23 or with a bevel Wheel 24. A control member26, which is pivoted at 27, engages the shaft 2h at 25. The controlmember 26 can be locked by means of a catch pin 28 cooperating withnotches 29, 3t) and 31. The control member 26 has an extension 32 whichcooperates with abutment 33. Another abutment 34 is adjustable by meansof a screw bolt 35 and also serves for influencing the control member 26as soon as it comes into contact with the counter abutment 34.

A worm wheel 37 is driven by a worm 36 which is in turn driven by apulley 66 shown in Figure 9. This pulley is belt-connected to pulley 55of motor 54. The worm wheel is connected with a hollow shaft 38 whichconstitutes a bearing for a spindle 39 which carries a bevel wheel 40.The spindle 39 can be screwed into and out of a slide 43 by means of ascrew thread 41 engaging in a counter screw thread in the slide 43. Thebevel wheel 40 meshes with the bevel wheel 23 and with the bevel wheel24. The carriage or slide 43 carries the crank pin 7 to which the rod isconnected (Fig. 4).

Referring to Figures 5, 6, 7 and 8, the king pin or king shaft 8referred to above is driven in the following manner: Hollow shaft 38carrying gear 45 drives the gear train comprising gears 46, 47, 48,shaft 49, change speed gearing 50, gears 51, and worm gearing 52, 53.Worm gear 53 is mounted upon the king pin or shaft 8 which as said abovecarries the cam discs 9 and for coaction with members 13 and 14.

The crank drive receives its rotary movement from the rotating worm 36which drives the hollow shaft 38 through the intermediary of the wormwheel 37, thereby imparting a rotary movement to the slide 43 andconsequently to the crank pin 7. The radial movement to lengthen orshorten the crank 6 is effected during the rotation of the pin 7 byadjusting the pin with the aid of the spindle 39. Its rotary movement isinitiated by actuating the control clutch 22 which is effected from theking-pin 8. If, for example, the cam 11 of the cam disk 9 comes intocontact with the counter cam 13 of the control fork during the rotationof the kingpin 8, the control fork 15 moves towards the left and liftsthe shaft through the intermediary of the sleeve 21, so that the clutchmember 22 connects the shaft 20 with the bevel wheel 23. As aconsequence the spindle 39 rotates so that the slide 43 is shifted, forexample, in the direction of the arrow D. At the same time the slide 43and with it the crank pin 7 continue to rotate. During the displacementof the slide 43 the abutment 33 comes into contact with the extension 32of the control member 26 causing the control member 26 to swing aboutthe pivot pin 27 until it is arrested in its middle position by theengagement of the catch pin 28 in the notch 30. If the cam 12 on the camdisk 10 comes into contact with the counter cam 14 of the crank 15, thiscrank is shifted towards the right, the shaft 20 being moved downwardsso that the clutch member 22 engages the bevel wheel 24. This againresults in a displacement of the slide 43. In this case the displacementof the slide 43 is in the direction of the arrow E. Consequently theabutment 34 contacts the counter abutment 34' so that the control member26 will be moved in clockwise direction, the catch pin 28 being shiftedout of the notch 31 and into the notch 30. As a result the clutch member22 again assumes its middle position.

The grinding operation proceeds as follows: The motors 54 and 60 areenergized by any conventional means (not shown). The grinding spindle 64and worm 36 are driven by their respective motors, and the king pin 8 isrotated by the above described gearing so that cam 11 engages withcounter cam member 13 which, by means of the linkage 15-16, moves shaft20 upward as shown in Figure 5. This movement is effective to engageclutch member 22 with the clutch member on gear 23 thus causing amovement of crank pin 7 outwardly in a radial direction as beforereferred to. The above described rotary movement of the slide 43carrying the crank pin in conjunction with the outward movement of thecrank pin causes, by means of the connecting rod 5, an oscillatorymovement of member 68, shaft 69, and consequently of the chuck 2, theamplitude of the oscillations increasing as the crank pin 7 moves awayfrom its center position. A point will finally be reached in the radialtravel of the crank pin at which abutment 33 contacts abutment 32, whichas stated above, will cause the disengagement of the clutch members onmembers 22 and 23. At this point, the chuck is at its maximum amplitudeof oscillation and the grinding operation proceeds at this stage untilthe cam 12 is rotated to such an extent that it engages counter cam 14.Such engagement causes a closing of the clutch members on member 22 andgear 24 and this in turn, due to the reversal of rotation of screw shaft39, as referred to hereinbeforc, will bring the crank pin 7 back to itscentral position. When this is reached, the abutment of member 34 withmember 34' will cause a movement of member 22 from clutching positionand into the neutral position shown in Figure 5. Under this conditionthe only movement imparted to the chuck is a rotative one, andconsequently, the machine is now in readiness for the finishing grindingoperation which now forthwith proceeds and which will form the grindingtrack of the character shown in Figure 3.

The crank pin 7 in moving from the middle point S, has moved outwardsthe length of the crank 6, then reversed and run back to S. As, duringthis time, the pin '7 rotates, an oscillating movement is maintaineduntil the crank pin 7 is in the position S. In this position. althoughit rotates, it does not in any way influence the connecting rod 5 orchuck 2. Consequently the finish grinding of the ring I is carried outwhen the crank pin 7 is in this position. By this means it is possiblewith the aid of suitable cam disks on the kingpin 3 to carry out thegrinding operation swinging the chuck relatively to the grinding wheeland a subsequent finish grinding operation without any swingingmovement, the angle of swing being determined by the abutment 34 whichcan be adjusted by means of the screw bolt 35.

I claim:

1. In an internal surface grinding machine having a tool holder agrinding tool held thereby and a chuck oscillatable the one relativelyto the other for grinding internal surfaces, such as the internalsurfaces of the rings for ball bearings, a driving and control apparatusfor controlling the commencement, the amplitude, and the duration of theoscillating movement of said chuck comprising a king pin, a rotary crankhaving an axis of rotation, a crank pin having a pin axis and carried bysaid crank to be automatically adjustable thereon from a predeterminedradial position with respect to said axis of rotation to a radialposition of coaxial alignment of said axis of rotation and of said pinaxis where the radial position is zero and vice versa, control means foroper-- atively connecting said king pin with said rotary crank toautomatically adjust the radial position of said crank pin between saidpredetermined radial position to said zero radial position thereof independence on the rotation of said kingpin, and a connecting rodconnecting said crank pin with said chuck to effect said oscillatingmovement and control the amplitude thereof dependent on said radialposition from a maximum thereof corresponding to said predeterminedradial position to zero corresponding to said zero radial position toeifect finishing in said latter position.

2. In an internal surface grinding machine, the combination according toclaim 1, wherein said crank pin carries a rotary slide, and wherein saidcontrol means includes means for shifting said slide in the radialdirection of said crank.

3. In an internal surface grinding machine, the combination according toclaim 1, wherein said crank pin carries a rotary slide, and wherein saidcontrol means includes means for shifting said rotary slide in theradial direction of said crank, said last-mentioned means including aspindle operatively connected with said slide and selectively operablemeans for stopping said spindle and selectively rotating the same inboth directions.

4. In an internal surface grinding machine, the combination as set forthin claim 1, further comprising a rotary slide mounted on said crank pin,a spindle operatively connected with said crank pin to shift said slidein the radial direction of said crank, and driving means cooperatingwith said slide including transmission elements and a coupling memberselectively engageable with either of said transmission elements toimpart rotary movement to said slide in opposite directions.

5. In an internal surface grinding machine, the combination according toclaim 1, further comprising a rotary slide carried by said crank pin, aspindle operatively connected with said rotary slide, drive meansincluding a clutch and transmission elements for drivingly connectingsaid spindle with said slide to impart to the latter a rotary movementin one or the other direction of rotation, a locking element for lockingsaid clutch in the disengaged position thereof and in each engagedposition, a shiftable shaft operatively connected with said lockingelement, and cam disk means operatively connected with said shiftableshaft to control the position of said clutch.

6. In an internal surface grinding machine, the combination according toclaim 1, further comprising a rotary slide carried by said crank pin, aspindle operatively connected with said rotary slide, drive meansincluding a clutch and transmission elements for selectively rotatingsaid spindle in opposite directions, a locking mechanism for lookingsaid clutch in the disengaged position and in each position ofengagement with one of said transmission elements, a shiftable shaftoperatively connected with said locking mechanism, and cam disk meansoperatively connected with said vshiftable shaft to control the positionof said clutch.

7. In an internal surface grinding machine, the combination as set forthin claim 1, further comprising a rotary slide carried by said crank pin,a spindle cooperating with said rotary slide to shift said slide in theradial direction of said crank, driving means including a clutch andtransmission elements operatively connected with said slide to impartrotary movement thereto in opposite directions, and locking means forlocking said clutch in the disengaged position and in each position ofengagement including a control member opposite said slide having anextension limiting the swinging movement of said control member, anabutment, and counterabutments cooperating with said abutment todisengage said clutch at the two extreme positions of the length of saidcrank.

8. In an internal surface grinding machine, the combi nation accordingto claim 7, wherein said abutment is adjustable to determine the maximumlength of said crank.

References Cited in the file of this patent UNITED STATES PATENTS857,791 Clark June 25, 1907 1,923,762 Stevens Aug. 22, 1933 1,927,552Long Sept. 19, 1933 2,168,843 Lockhart Aug. 8, 1939 2,176,154 ShannonOct. 17, 1939

